Lords of the rings: understanding tree ring science

Sure, you can tell how old a tree is by counting its rings, but those light …

Ask any second grader what you can do with the rings on a tree, and they'll respond, "Learn the age of the tree!" They're not wrong, but dendrochronology—the dating of trees based on patterns in their rings—is more than just counting rings. The hundred year-old discipline has given scientists access to extraordinarily detailed records of climate and environmental conditions hundreds, even thousands of years ago.

The ancient Greeks were the first people known to realize the link between a tree's rings and its age but, for most of history, that was the limit of our knowledge. It wasn’t until 1901 that an astronomer at Arizona's Lowell Observatory was hit with a very terrestrial idea—that climatic variations affected the size of a tree's rings. The idea would change the way scientists study the climate, providing them with over 10,000 years of continuous data that is an important part of modern climate models.

A. E. Douglass, the astronomer in question, is revered as the father of dendrochronology even though one of the field's basic concepts—crossdating, or the matching of ring patterns between trees—was independently discovered on four earlier occasions. (Pioneering computer scientist Charles Babbage was among that group.) Douglass was the first to apply truly scientific rigor to the study of tree rings, using a quantitative approach to tie variations in ring width to available climate records.

For the next dozen years, Douglass scoured Arizona for Ponderosa pine—dead or alive—to construct his first chronology. Completed in 1914, Douglass's chronology stretched back nearly 500 years, a feat accomplished by crossdating. Months later, Douglass teamed with an anthropologist to date timbers in pueblos in the American Southwest. For the rest of his life, Douglass continued to develop the science of dendrochronology. Though he was never able to tie sunspot activity to ring patterns—his original inspiration—his new field found favor with climatologists.

A bit of the basics

Dendrochronology operates under three major principles and a handful of other ground rules. The uniformitarian principle is perhaps the most important. It implies that the climate operates today in much the same way it did in the past. The uniformitarian principle does not imply that the climate today is the same as it was in the past, or even that today's climatic conditions ever occurred in the past. It simply states that the basic processes and limiting factors are consistent through time.

The second principle is that of limiting factors, where an organism's growth rate is constrained by the resource which is most limited. The third principle—crossdating—we've already covered. In addition to these three pillars, dendrochronologists must also pay close attention to where the trees grow. The best specimens are those at the margins of suitable habitat, which are sensitive to minor changes in environmental conditions. Finally, like all good scientists, dendrochronologists must be sure to gather a sufficient number of samples.

Before we get too far, we should cover the basic biology behind tree rings. Rings are formed by changes in a tree's growth rate throughout the year. As trees grow, the thin layer of living tissue just beneath their bark (the cambium) lays down new cells on top of older ones. As the cambium expands outwards, the oldest cells die off, leaving their lignin-hardened cellulosic exoskeletons behind.

Early in the season, trees grow rapidly, and the cells they build at this time are the largest of the year. As the season continues, the growth rate tapers off and cells become progressively smaller until just before winter, when growth slows or ceases. This change in cell size produces the characteristic banding pattern seen in cut wood. Trees in temperate climates produce the most obvious rings, thanks to the large difference in growth rates between the early and late season. Most tropical trees grow at a more or less constant rate throughout the year, making their rings less distinct.

Dendroclimatology, or the study of climatic influences on tree rings, is a large speciality within dendrochronology, and it's easy to see why. Trees not only recorded the last 10,000 years of climate history, they did so on every continent except Antarctica, bequeathing climatologists with an exquisite data set rich in both spatial and temporal detail.

Stressed is best

Trees—both living and dead—are not hard to find, but quality tree ring series are not as easy to come by. Forests with rich soil, gentle topography, and plenty of rainfall will produce gorgeous trees with lousy rings. On the contrary, trees living on steep slopes and in harsh climates are prized for their sensitivity. Scientists seek out trees living on the edge, sometimes literally. One of my undergraduate research projects demanded a rope and safety harness just to sample the trees.

Extracting a core from an increment borer, a standard tool used by dendrochronologists.

Photo by Tim De Chant

Finding a tree is only half the battle. Once researchers find a stressed tree, they need to estimate where the pith sits within the tree, bore into it with what amounts to an overpriced, hollowed-out drill bit, and remove the core in one piece. Once removed, they take the core back to the lab, mount it, surface it (with a sander or a razor blade), and measure its rings. Scientists used to do that last part by hand, but software coupled with a properly calibrated scanner can now both identify rings and measure their widths.

A prepared tree core under magnification. Note the small rings. This tree is either really slow growing, really stressed, or both.

Raw measurements, though, are of little use. As trees age, their growth slows, and declining trends must be eliminated from the data. These standardized measurements are the meat and potatoes of dendroclimatology. Big fat rings indicate a favorable year, small narrow rings are evidence of the opposite, and the overall pattern gives a snapshot of the climate throughout the tree's life. With these measurements in hand, dendrochronologists can use the principle of crossdating to search for other samples with matching patterns.

Unfortunately, ring data is not always straightforward. Trees are fickle organisms. Sometimes they appear to skip growing for a year. Other times they may grow on the southern side and not the northern. Sometimes spring comes early, the summer is cool and dry, and the fall is warm and wet, causing the tree to grow quickly, then slowly, then quickly again before winding down for the winter, giving the illusion of two years of growth.

To weed out these problematic patterns, dendrochronologists gather dozens of cores from each site and time period. Using statistical analyses, a site chronology can be created that integrates ring data from each individual tree, reducing the influence of tree-to-tree variation and maximizing the climate signal. From numerous site chronologies, master chronologies can be constructed that further reduce the noise caused by variations from different sites.

You lost all credibility when you used the expression 'climate change deniers'. This is basically a sneer whose purpose is to imply that informed good faith doubt about any part of the Party Line on Global Warming is impossible.

The fact is that AGW is a complicated hypothesis with a large number of working parts, some of which are better understood and better validated than others, and 'denier' is not an appropriate categorization of people who are skeptical about whether some elements of it have been proven beyond reasonable doubt. Tree rings are one of the most dubious parts of the Party Line. You can be skeptical about tree rings without being skeptical about a lot of the rest of the AGW hypothesis.

A comparison might illuminate. Vaccines are a complicated topic. It is an article of faith in the WHO that large scale vaccination with the standard multiple vaccine of children of both genders in third world countries saves lives. If you are skeptical that this particular vaccine as currently administered does actually save the lives of female infants, you are not a 'vaccination denier'. You do not even doubt the efficacy of the multiple vaccine. What you doubt is that it is being administered appropriately in terms of the age of the infant, the gender of the infant, and the timing of other vaccines being given. This is a reasonable scientifically based doubt and calling people who draw attention to evidence about it 'deniers' will not make the facts of high female child mortality go away.

In a different but similar way, the tree ring = thermometer hypothesis is peripheral to AGW, and no purpose is served by calling people who doubt it 'climate change deniers'.

As to the divergence problem, its a pretty simple issue. If we calculate temperatures from tree rings, and then compare them to measured temperatures, they should correlate. If they do not, then we have a problem. One explanation could be that they are not thermometers. They do not correlate where we can check them. and for the period where we do not have temperature measurements, the tree rings won't measure temperatures accurately either. After all, if the only evidence they are thermometers comes from the period of overlap, and if this period shows poor performance, they probably perform equally erratically over the whole of history. How far off they are we cannot tell if this is true. They are just not thermometers, period.

The other explanation would be that they are accurate, and that something bad has happened to recent temperature measurements.

Neither explanation is very comfortable. The first implies that all those studies based on MBH 98 are worthless (not even counting the issues with Bristlecone Pines and Gaspe Cedars and too small numbers of samples in the early years....).

The second implies that it is not really as warm as the surface temperature record seems to be saying it is.

We have a problem here, and its not that tree ring skeptics are 'deniers'. The ones who are in denial are the ones calling those of us with our eyes open by that name. For more insight into this by the way, read the Climategate emails, particularly Keith Briffa's remarks on the subject.

So you complain about the term 'climate change deniers' then go and use the term 'Party Line' multiple times. Then bring up the emails again, which you probably looked at without checking out their data. Yep, you sound like the typical 'denier' to me.

Publishing this creaky article now makes for a perfect juxtaposition to the frantic CES coverage and creates that perfect blend of flavours that makes for a perfect ARS dish (sorry, OD on Masterchef Australia)

I had a feeling this, tragically like many science issues, would become polluted with politics.

If only those who fall in step to the propaganda of the demagogues would abandon their ideologies.

I leave you with this perspective, which if embraced in our dogmatic strife filled globe, would change the world;

“When Kepler found his long-cherished belief did not agree with the most precise observation, he accepted the uncomfortable fact. He preferred the hard truth to his dearest illusions; that is the heart of science.” – Carl Sagan

I understood the carbon isotope usage difference, but the oxygen-16 / oxygen-18 explanation included no statement of the cycle's preference for one isotope over the other. With that in mind it would appear that in the statement:

Quote:

Water molecules containing oxygen-16 will escape first because of their lighter weight, making that day's sugars richer in oxygen-18. If it's a cool, moist day, less water will evaporate. If the weather continues to be cool and wet for many months, then that year's rings will also be richer in oxygen-18. The converse is true of hot, dry years.

the last reference to oxygen-18 might ought to be oxygen-16 since the long-term result of cool weather ought to be less oxygen-16 loss through evaporation.

If this was an article about pure science, why would you cake about what types of people believed it or not? Why fan the flames with "climate change deniers"? what places does that have in a pure science article?

If you're writing an article about science, you talk about the evidence, how you analyze the evidence, and any caveats, who cares who believes it or not. It's for the reader to decide whether he/she believes it, or study it further. This article went from: interesting article about an area of science, to axe to grind with THOSE people.

If this was an article about pure science, why would you cake about what types of people believed it or not? Why fan the flames with "climate change deniers"? what places does that have in a pure science article?

If you're writing an article about science, you talk about the evidence, how you analyze the evidence, and any caveats, who cares who believes it or not. It's for the reader to decide whether he/she believes it, or study it further. This article went from: interesting article about an area of science, to axe to grind with THOSE people.

Science doesn't exist in a vacuum. Anybody who pays any attention to the use of tree rings in climate is aware that they're mired in a (largely manufactured) controversy. Hell, the divergence problem is the "decline" in the "hide the decline" quote that was all over the internet for a while.

The goal of this article was to inform our readership. Pretending that the one piece of information that the public is most likely to know about doesn't exist wouldn't do anything to meet that goal.

You lost all credibility when you used the expression 'climate change deniers'. This is basically a sneer whose purpose is to imply that informed good faith doubt about any part of the Party Line on Global Warming is impossible.

And you lost all credibility when you capitalized "Party Line on Global Warming".

Ally wrote:

A comparison might illuminate. Vaccines are a complicated topic. It is an article of faith in the WHO that large scale vaccination with the standard multiple vaccine of children of both genders in third world countries saves lives. If you are skeptical that this particular vaccine as currently administered does actually save the lives of female infants, you are not a 'vaccination denier'. You do not even doubt the efficacy of the multiple vaccine. What you doubt is that it is being administered appropriately in terms of the age of the infant, the gender of the infant, and the timing of other vaccines being given. This is a reasonable scientifically based doubt and calling people who draw attention to evidence about it 'deniers' will not make the facts of high female child mortality go away.

Your comparison is only illuminating the fact that you also don't understand evidence based medicine. It's not an article of faith that standard multiple vaccine of children of both genders would save lives. Based on immunization evidence in other areas of the world, it's reasonable to assume that immunization in West Africa would be similarly effective. No one took this on faith, and epidemiologists followed the program to asses for morbidity and mortality. I assume you're referring to the increased mortality of female infants after getting the high titre measles vaccine. This was also given based on evidence that in West Africa, where measles mortality is high and mothers have high immune titres, that a stronger vaccine would be beneficial. Unfortunately, they also changed the order of vaccination, and these children got their DTP-IPV after the measles vaccine. Apparently, killed vaccines provide less non-specific protection, while live vaccines (measles) provide more non-specific protection from other illnesses in infants. This increased mortality was compared to infants who received the standard series and low titre (standard) measles vaccine. Overall immunized children do much better in West Africa than non-immunized (even in the case of the high titre measles vaccine), both male and female, and there is plenty of epidemiology to back this up. Among hospitalized children, mortality was higher overall for children who got IPV/DTP and lower for those that got measles vaccine (more pronounced for females). Again, this if from infections not covered by DTP/IPV, overall there is a benefit because they were protected from those common childhood diseases. So at this point, if you were to claim there might be a better order to give vaccines, or that female infants get more protection from live vaccines than males, you would not be a "vaccine denier", there is evidence to back this up. If you were to claim, however, that the standard multiple vaccine of children in the third world doesn't save lives, you would be a "vaccine denier", because there is clear evidence this is not true.

Interesting, very interesting article. Please give a bit more depth to the thought process with the divergence problem.

From what I understand we've only got about 150 or so years of temperature data, only about a hundred+ (going back to the early 1900s) is where we were getting really serious about tracking and making sure we found a way to keep those records around. right?

The divergence problem, from my understanding, also rears its ugly head around the 1960s, roughly 50 years ago, and continues to this day, correct?

So... somewhere between 30 to 50+% of your derived climatic data from these trees is completely disconnected from observations and the period of observation that is considered the most accurate out of the entire dataset is within that.

Amazing. The article raises the relatively minor 'divergence' problem, but entirely fails to mention the major controversy over tree-ring derived temperature reconstructions like Mann, Bradley and Hughes 98 (The famous 'Hockey Stick').

In many eyes these reconstructions have been shown to be worthless because of deeply-flawed statistics. See, for example, the McShane and Wyner paper published in 2010 which comprehensively demolishes MBH.

Reading the article you would form the impression that dendroclimatology was basically sound science with a few small wrinkles still to be settled. In fact it might prove to be worthless as a reliable guide to past climate

Stop Ars. Just stop it. You're not a scientific journal and you don't need to be throwing more fuel on the fire. Do you create the message or just report it?

The fact that you used the 'denier' word means you're politically motivated, and Ars has always drank the cool aid.

This is a proxy defense for the failing Mann tree-ring research. The Mann paper is criticized for its statistical manipulation of its data set, its limited number of cores, and its core selection, especially when better datasets existed. <i>"In other words, our model performs better when using highly autocorrelatednoise rather than proxies to ”predict” temperature. The real proxies are less predictive than our ”fake” data. While the Lasso generated reconstructions using the proxies are highly statistically significant compared to simple null models, they do not achieve statistical significance against sophisticated null models."</i> ( http://wattsupwiththat.com/2010/08/30/b ... -et-al-99/ )

If I am to continue to enjoy Ars, I need Ars to stop publishing these position pieces, or at least present the other side of the debate. (And 'debate' is a valid 'd' word)

Interesting, very interesting article. Please give a bit more depth to the thought process with the divergence problem.

From what I understand we've only got about 150 or so years of temperature data, only about a hundred+ (going back to the early 1900s) is where we were getting really serious about tracking and making sure we found a way to keep those records around. right?

The divergence problem, from my understanding, also rears its ugly head around the 1960s, roughly 50 years ago, and continues to this day, correct?

So... somewhere between 30 to 50+% of your derived climatic data from these trees is completely disconnected from observations and the period of observation that is considered the most accurate out of the entire dataset is within that.

How do you not consider this a very very large problem?

Because as the article states, it's only diverging for trees in the far north (circumpolar). Tree ring data from other areas is consistent with temperature data. Also, all of global temperature and climate study is not based on tree rings, it's just one piece of the puzzle.

Well folks, you tell me. What makes someone a climate change denier? Can you doubt dendro and not be one? Can you be a denier and not doubt dendro? To be a denier do you have to doubt that the climate changes, or can you also be one if you think its happening but doubt its CO2 that causes it?

Like with vaccines. Are you a vaccine denier if you think vaccine is in general a great lifesaver, but in some particular cases not?

Skeebo and others, with respect to the divergence problem: bbonish is correct in that the only trees that suffer from this issue are at high latitudes. The rest of the trees still follow the trend (the baby with the bathwater analogy is apt). Also, there are a number of physiological reasons why northern trees face greater stresses due to climate change, reasons which I outlined in the section titled "The 'divergence problem'".

I'm not making these explanations up. When I first read about the divergence problem, I immediately thought of water stress brought on by changes in climate (after all, it was one of the main themes in my dissertation). Researching it further, I was pleased to discover other scientists published this and other explanations in respected peer-review journals. If I can think of a plausible explanation for the divergence problem in a few minutes, you can be sure that there are experiments underway that will lift the veil off the issue.

As for "deniers" vs. "skeptics", I've grown weary of covering for people who choose to ignore a large body of scientific evidence and instead focus on minor points that do not fit with prevailing theory/thought/consensus. "Skeptic" is just a convenient term for these people to hide behind, to make it sound like they are contributing to science. In reality, most "skeptics" are armchair scientists (or if they are experts in some field, armchair climate scientists) who likely have some deep seated reason why they choose to deny that anthropogenic climate change is happening. There is no debate about whether it is happening. The only debate is whether we should do something about it.

Timmy and bbonish, I understand that it only affects the northern latitude trees (and the southern most as well, correct?... except that their is less land mass in the lower latitudes).

How does this not invalidate the derived data in the Northern latitudes entirely... where, incidentally where we find some of the coldest temperatures and the lowest number of temperature stations?

Also, you kinda gloss over this... but trees in good soil, in high rainfall areas don't generate good results? How good is the coverage in the tropical regions then?

Sounds like you got a technique that is decent to good for extracting the localized historic climatic conditions in very specialized situations, given the assumption that there have been no fundamental changes to the basic behavior of the climate system (which is a fair assumption going back a few thousand years) and that we fully understand that climate system (which is an arguable claim, there is always something new we're learning).

Skeebo and others, with respect to the divergence problem: bbonish is correct in that the only trees that suffer from this issue are at high latitudes. The rest of the trees still follow the trend (the baby with the bathwater analogy is apt). Also, there are a number of physiological reasons why northern trees face greater stresses due to climate change, reasons which I outlined in the section titled "The 'divergence problem'".

Is that why Mann choose them (the latitudes with divergence) for the hockey stick graph?

TimmyDee wrote:

As for "deniers" vs. "skeptics",...There is no debate about whether it is happening. The only debate is whether we should do something about it.

Apparently, there is some debate about whether it is happening in the latitudes with divergence...

You've already chosen a side and so you scientific contribution is nullified. You must continually be able to reevaluate data, but you've put that segment of data to rest. The earth is the center of the universe, and onto other things you say.

Science doesn't exist in a vacuum. Anybody who pays any attention to the use of tree rings in climate is aware that they're mired in a (largely manufactured) controversy. Hell, the divergence problem is the "decline" in the "hide the decline" quote that was all over the internet for a while.

The goal of this article was to inform our readership. Pretending that the one piece of information that the public is most likely to know about doesn't exist wouldn't do anything to meet that goal.

I didn't say don't talk about it. I'm saying, if the goal was to inform your readership, then simply inform your readership. It's not necessary to single out a group of people and label them "deniers" (which is a very politically charged word). You're just inviting a worthless discussion that's going to fall away from the article. What discussion could you have on the subject if you label critics as "deniers"? You're basically stating that what you argue is right, and anyone who believes different is denying the truth, there's not discussion to be had with this attitude.

The article gains nothing from having that in there. If you took out all instances of "climate change deniers" the article would have been still great. Except now, the discussion is going to be clouded with political name calling, instead of actual discussion on the science itself.

Skeebo, the northern latitude trees have not been thrown out pre-divergence because those records can be compared against other climate proxies like ice cores and sediment cores. Sort of like the old geometry proofs (i.e. side-angle-side).

Tropical trees are trickier, but the key is to find trees that are at their margins. This may mean finding trees on even poorer soils (many rainforests have incredibly poor soils to begin with—all the nutrients are held in the biomass) or ones that are on a hill and more exposed to the elements. Since tropical trees grow year round, their rings are not very distinct. The same thing happened with the coast live oak trees I studied in grad school—many broadleaf evergreens slow their growth in winter, but not as much as deciduous trees. It is possible to pick out rings, just not as easy as with pines, sugar maples, etc.

As for generalizing, it is possible. All trees operate under the same basic physiological principles (they are C3 plants). So long as those principles remain unchanged (and they haven't really for millions of years), we can compare across different species by comparing the relative changes in ring widths instead of absolute changes. It's all about the patterns. Certain years for certain trees in certain places may deviate, but more general trends are visible when using large data sets like the kinds used to build climate reconstructions.

Wait, you're comparing proxies to proxies for verification and you think that is ok? That's insane man!

You're comparing estimates to estimates and calling it the truth? That's the exact same thing that the accountants for Enron were doing.

You can be comforted that what you are doing isn't uncommon, many others have done it before you and your field. Unfortunately, almost universally the outcome has been disastrous.

This isn't some geometry proof were there is one verifiable answer and technique that can be found and then that technique applied elsewhere. Even if your comparisons are valid they would require an impossible amount of detail, each core would have to be independently calibrated and verified, especially considering that each core isn't really good for more than a semi-local approximation of the climatic behavior.

Look I doubt you'll give much credence to what I'm saying, but your field has a major problem with thinking this practice is ok and you're interpreting way more than is actually there.

Science doesn't exist in a vacuum. Anybody who pays any attention to the use of tree rings in climate is aware that they're mired in a (largely manufactured) controversy. Hell, the divergence problem is the "decline" in the "hide the decline" quote that was all over the internet for a while.

The goal of this article was to inform our readership. Pretending that the one piece of information that the public is most likely to know about doesn't exist wouldn't do anything to meet that goal.

I didn't say don't talk about it. I'm saying, if the goal was to inform your readership, then simply inform your readership. It's not necessary to single out a group of people and label them "deniers" (which is a very politically charged word). You're just inviting a worthless discussion that's going to fall away from the article. What discussion could you have on the subject if you label critics as "deniers"? You're basically stating that what you argue is right, and anyone who believes different is denying the truth, there's not discussion to be had with this attitude.

The article gains nothing from having that in there. If you took out all instances of "climate change deniers" the article would have been still great. Except now, the discussion is going to be clouded with political name calling, instead of actual discussion on the science itself.

Part of informing is dispelling misinformation, which the climate change deniers spread. They are part of Ars's readership as well, and I have no doubt that they would have come into this thread with the very same arguments had it not been mentioned. They have a tendency to do that. This way, the rebuttal is already right there in article.

Amazing. The article raises the relatively minor 'divergence' problem, but entirely fails to mention the major controversy over tree-ring derived temperature reconstructions like Mann, Bradley and Hughes 98 (The famous 'Hockey Stick')

Scorp1us wrote:

This is a proxy defense for the failing Mann tree-ring research. The Mann paper is criticized for its statistical manipulation of its data set, its limited number of cores, and its core selection, especially when better datasets existed.

Oh my, you two are dense. Mann addressed this in 2008 by surveying lots of proxies, and even omitting tree rings entirely. And guess what? The climatological conclusions don't change. The damn "hockey stick" still exists. I swear I've posted this more than a dozen times.

Quote:

From the abstract:Recent warmth appears anomalous for at least the past 1,300 years whether or not tree-ring data are used.

The other proxies have been calibrated, too. I'm not saying that scientists compare proxies to proxies and declare they've found something. The idea is that if all these proxies are saying the same thing, why throw out tree rings if a trend in a few points has not yet been explained?

Skeebo and others, with respect to the divergence problem: bbonish is correct in that the only trees that suffer from this issue are at high latitudes. The rest of the trees still follow the trend (the baby with the bathwater analogy is apt). Also, there are a number of physiological reasons why northern trees face greater stresses due to climate change, reasons which I outlined in the section titled "The 'divergence problem'".

Is that why Mann choose them (the latitudes with divergence) for the hockey stick graph?

TimmyDee wrote:

As for "deniers" vs. "skeptics",...There is no debate about whether it is happening. The only debate is whether we should do something about it.

Apparently, there is some debate about whether it is happening in the latitudes with divergence...

You've already chosen a side and so you scientific contribution is nullified. You must continually be able to reevaluate data, but you've put that segment of data to rest. The earth is the center of the universe, and onto other things you say.

No, there is no "debate" about whether this is happening in latitudes with divergence. There is debate about why there is a divergence between tree ring data and other sources, but the increasing temperature is not in question. There are plenty of papers showing the same trends not using tree ring data. Here is one showing the trend with and without:

Heheh. I keep that paper bookmarked But it's trival to find -- if one of these nitwits typed "mann" and "tree ring" into Google Scholar, it should be on either the first or second page of results (Just checked, and it's actually the top hit if you restrict to papers "since 1992").

Part of informing is dispelling misinformation, which the climate change deniers spread. They are part of Ars's readership as well, and I have no doubt that they would have come into this thread with the very same arguments had it not been mentioned. They have a tendency to do that. This way, the rebuttal is already right there in article.

So this is less of a science discussion and more of a "bait the deniers" article?

So you take this article on faith that whatever is written in it is absolute fact, and use it to beat any hapless "deniers" who wander in here, over the head with it.

The fact that you used the 'denier' word means you're politically motivated, and Ars has always drank the cool aid.

And the fact that you use terms like "drank the cool aid" suggests you're not?

Let's take a look at this post in some detail, since i think it actually demonstrates denialism in action:

Quote:

This is a proxy defense for the failing Mann tree-ring research.

Lots of other people do tree ring research; this is explaining why it's considered valid science. So, we have failure to recognize a scientific consensus on the validity of this approach, in favor of some sort of conspiracy theory about why we published this.

Second, there's a failure to recognize reality. In 2003, that National Academies of Science convened an expert panel on recent climate reconstructions. It showed that multiple proxy methods, performed by many different labs, have all produced climate patterns that largely track Mann's results. Mann himself has published updated papers that perform the same analysis with and without any tree ring data; these also produce a the same temperature trends. In short, the hockey stick appears to be a real and accurate description of recent climate trends. But, by denying the latest research, you can call one practitioner's work "failing," and go on to say this:

Quote:

The Mann paper is criticized for its statistical manipulation of its data set, its limited number of cores, and its core selection, especially when better datasets existed.

Which Mann paper? There's several. Why not consider any of the papers from other research groups that have shown essentially the same thing? Why not look into whether some of the criticisms are valid, whether they've been corrected, etc? You just appear to be repeating things you've read elsewhere, and assuming their accuracy, rather than looking at credible sources like the NAS.

In short, you appear to be using some problems in a paper that's over a decade old to deny any further research results in this field.

Quote:

<i>"In other words, our model performs better when using highly autocorrelatednoise rather than proxies to ”predict” temperature. The real proxies are less predictive than our ”fake” data. While the Lasso generated reconstructions using the proxies are highly statistically significant compared to simple null models, they do not achieve statistical significance against sophisticated null models."</i> ( http://wattsupwiththat.com/2010/08/30/b ... -et-al-99/ )

Here, he's quoting a denialist (and i have no compunctions about using that here - Watts denies that the temperature has even risen) blog quoting a paper McShayne and Wyner. That paper describes different statistical methods for examining proxy data. Although it concludes that a hockey stick is the most likely trajectory, it's calculates that it is not statistically significant. Whether the different methods used in that paper are more or less accurate than the original methods remains an area of active debate.

Quote:

If I am to continue to enjoy Ars, I need Ars to stop publishing these position pieces, or at least present the other side of the debate. (And 'debate' is a valid 'd' word)

My conclusion, based on the above, is that you have a grossly distorted view of what any valid scientific debate on this topic is about, caused by reading unreliable sources of information. I suspect, were we to actually do a story on the areas in this field that are open to scientific debate, you'd be surprised to find that the "other side" you think exists doesn't appear, because it's not engaging with the science. And you'd dismiss the article as a "position piece" as well.